I'd say the Allison T40. Allison stuck two T38's side by side. The result was a garbage turboprop engine.

I did not sell very well, so Lockheed killed me. I'm the reason it doesn't make airliners anymore.

Random stuff:
1. They ain't "sharklets", like Turbofan said.
2. The Tu-114 should really go back into service in a redesigned form.
3. The L-1011 should also return, too.
4. My posts are repeatedly deleted on the AM3 forum.
5. Concorde must return!
6. Fegelein can never die, even when Hitler himself tries to kill him. (Downfall parodies)
7. Embraer should restart production of the EMB-110 and EMB-120, as those are my two favourite prop planes.

Dual Turboprops aren't that bad, especially when you consider the success the T40 had in VTOL.

If you want the worst engines look at some of the German WW2 projects which did stupid things like two engines in a nacelle

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Really?
On one occasion, the engine was shut off, only it kept running on leaking oil. They eventually had to destroy it by throwing a bucket of bolts into the engine to get it to shut down. That was during a test run of the engine.
In addition, the engine was highly unreliable, and would tear itself apart on occasion. An R3Y Tradewind suffered a catastrophic engine failure, and it collided with a seawall. It had problems with propeller control and gearbox.
The XF-84's propeller governor would start surging when it got to around 400 kts (source: https://www.airspacemag.com/how-things- ... 49/?page=3 , testimony by a test pilot).
The only thing it was good at was in powering the Hiller X-18, and they just gave up on that. In my opinion, that was actually a sound design, save for the T40 engines.

I'll also throw in the R-3350 in it's early iterations. While it has proven itself an excellent engine, Wright rushed it into production. It had poor cooling, and used magnesium in the crankcase, so the magnesium would actually light on fire. The B-29, the aircraft that originally used it, suffered a lot of crashes because the fire would literally burn through the wing.

I did not sell very well, so Lockheed killed me. I'm the reason it doesn't make airliners anymore.

Random stuff:
1. They ain't "sharklets", like Turbofan said.
2. The Tu-114 should really go back into service in a redesigned form.
3. The L-1011 should also return, too.
4. My posts are repeatedly deleted on the AM3 forum.
5. Concorde must return!
6. Fegelein can never die, even when Hitler himself tries to kill him. (Downfall parodies)
7. Embraer should restart production of the EMB-110 and EMB-120, as those are my two favourite prop planes.

Haha, actually made me laugh. The "wing" jerking up and down makes it seem like a quasi-ornithopter.

I did not sell very well, so Lockheed killed me. I'm the reason it doesn't make airliners anymore.

Random stuff:
1. They ain't "sharklets", like Turbofan said.
2. The Tu-114 should really go back into service in a redesigned form.
3. The L-1011 should also return, too.
4. My posts are repeatedly deleted on the AM3 forum.
5. Concorde must return!
6. Fegelein can never die, even when Hitler himself tries to kill him. (Downfall parodies)
7. Embraer should restart production of the EMB-110 and EMB-120, as those are my two favourite prop planes.